Clinical response of thyrotropin-secreting macroadenoma to bromocriptine and radiotherapy

A patient presenting with hyperthyroidism was treated initially with antithyroid drugs and subsequently radioiodine. Thereafter he was noted to have inappropriately elevated thyrotropin. A bitemporal visual field defect was noted and CT scan confirmed the presence of a pituitary tumour. TSH was elevated and unresponsive to TRH stimulation. alpha subunit was not elevated. Long-term bromocriptine therapy (doses up to 50 mg/day) resulted in partial, but incomplete suppression of thyrotropin secretion. Following radiotherapy there was resolution of the visual field defect; the TSH, however, remains elevated at greater than 20 mU/l. Radiotherapy and bromocriptine may provide a clinically useful alternative to pituitary surgery in patients with TSH-secreting macroadenoma with suprasellar extension.